High-potential electric switch



Jan. 22 1924.

G. A. BURNHAM HIGH POTENTIAL ELECTRIC SWITCH a Filed March 12 1921 2 Sheets-Sheet 1 '6. A. BURNHAM HIGH POTENTIAL ELECTRIC SWITCH ,Filed March 12. 1921 2 Sheets-Shut 2 I71 var-@7 07:

k-WW Patented Jan. 22; 1924.

' UNITED STATES PATENT OFFICE.

GEORGE A. BURNHAM, OF SAUGUS, MASSACHUSETTS, ASSIGNOR T SEARS B. CONDIT,

OF BBOOKLINE, MASSACHUSETTS.

HIGH-POTENTIAL ELECTRIC SWITCH.

Application filed March 12. 1921." Serial! No. 451,921.

To all whom it may concern:

Be it known that I. Gnonon A. BURNHAM, a citizen of the United States; residing at Saugns. in the county of Essex and State of (Massachusetts. have invented an lmprovement in High Potential Electric Switches of which the following is a specification.

This invention relates to electric switches and has particular reference to oil immersed switches adapted to control circuits of relatively high potential.

For the control of circuits of'say 50,000 volts and above, it has been common practice to provide a separate switch for each phase of emulti-Phase circuit and, because of the relatively great distance provided between the conducting and other components of the switch, made necessary to provide sufficient insulation of the" conducting components, each switch unit has relatively great bulk and iscorre's'pondi ngly expensive. The installa'tion 'expelise'of' the switches, also, is

considerable the switchun'i'ts are u's'ually' l mofinted'on concrete foundationsi 1 Also by r'easew'af their bulkfdifiiculties are ex'- perienced in shippingtlieni'from the factory 1:02 t irisltalletion lo'cetion and transportatinfifiiri's'rls Ar: onsiderahle." -The switches are: yente'd a nilgf wliile'they are more or'les's weatherV geafiyeIeue toexpansion' and contriiotiolig of the" air end other gases in the nx nsi nge aee m' the switch, due to variatijolis' df iat nio's'pheric temperaturel'an a pi'cie hle 'iinionntoflnoisture collects in tl i switch alndjmix es with'the oil andimpairs its insulating pproperty. 'With'high potentials a. relatively small amount ofwa-ter in the oil will'break downthe oil insulation of the conducting f comp'onents of the switch Furthepno ffiv the viscosity of theoil .in the sfefie'chd liyifiemp mt e a g an d i jxi' winter the oiljthick'ens or; b comes more viscous with thei-e'sult that the speed I of the movable switchmemhers to open posinon,- zmd, consequentlm' the current interrupting capzicitj of the switch, is reduced.

object ofithisinvention is to provide an oilsw itch adapted tocont-rol circuits of relatively high potential, of relatively si mple and inexpensive construction, wherein allthe switch members for a multi 'phase circhit, maybe contained in a'comnion casing; thz'tt is so arrangedtlmtthe oil will be kept at substantially constant temperatiufe at all times; which may have a relaitivly high head of oil above the contact member whereby to improve the interrupting capacity; and which will occupy but relatively little space when in transportation.

A further object of the invention is gen-. erally to improve the construction and op eration of an" electric switch.

The switch embodying the invention is mainly fabricated at the place of installation. Instead of providin large oil receptacles of sheet steel to contain the switch members I sink a pit-into the-ground and line the pit with, preferably, reinforced concrete to form the oil container; and the lined pit is made/of snliicient size to contain all switch members offa'rn' filti ph'ase circuit. The expense of preparing the concrete-lined pit may notgreetly exceed the cost of mak ing the concrete foundation necessary to sup port the'usual super-surface type of switches." The depth of the 'pitis preferablysnch' that the major portion of the body of oil wil be below firostile'vel wherebyithetenipblal tire of the oil ,will""reme,in1 practically constant throughout all the seiisonsifof' the ear-"11nd, in; any event. the temperajiure li ii ivill he reduced. The emanating co11311) JI;ie'iits"al 're carried by an inex e sive fiaineedhstrtfeei qn and supported front the jside of'tlifp'it' and suliirierged' benefits the oil; find-'='oiiii j saving in insulator ciis'ts'f'diitlfg'thdfib Iner'gence of insulators, 'w'ill -fii:ted3.

The e pansion ehsmter" (if thejfs'wilfch is" r'elati vely great and 'the cifi'rent-interi'ui'iting capacity correspondingly increa sedi." Qfip rent'.and 'potenti'altransformers may iil s 'obe im'rnerse'd in the oil, andalso the st'vi-tcli 6f)- eratiiig'mechani smi i i" Fig, l is 'h v'rti'cals'ection o f'a's'iili sil'rfice electricswi'tchf'einbocljififth intestine. i

Fig, 2 is a' transversefs'ection'bfthe of Fig. 1. "I I Fig.3 is a. plan detail'o'f' the cover of'the' switch.

' Fig. 4 is a."vertical section of the stationary switch members In carrying outth'e invention ii-well'or pit 10, preferably; cvlindrical, although itinia y be of other suitable' s'ha e, is sunk below the surface A of magmas to a"suitable depth. The pit is lined with 'concreteor jother suitable material to form' anoil' container 12 and the inner" face of the' container is mega smooth and mey be'given a superficial 01limperme'able coating.- Reinforcing fi'lifihers '13 may be incorporated inthe walltof. the container to reinforce and strengthen it. The stationary switch members 14: and movable switch members 15 and operating mechanism 16 may be supported on the frame 17 which latter may be secured, preferably removably, to stationary supporting members ]8 inset in the wall of the container and ex tended into thc'oil space. The oil in the coutainer is adapted to extend above the top of the stationary switch members so that said members will becompletely submerged. \Vith this arrangement it"is practicable to use oil-filled insulators for the stationary switch members which type of insulator previously has been found to be impracticable in many instances because of the difficulty of maintaining it full of oil.

Fig. 4 illustrates such an oil filled insulator wherein the conducting rod 1-9 of the stationary'switch member is enclosed within and spaced from the-wall of the tubular insulator 20 by'thespaceal which is adapted to-be filled with oil. The insulator, with this arrangement, serves'principally to support' the switch member mechanically a nd c0nseqnently can be cheaply constructed. Current .transformers 22may be disposed about certain of the insulators 20 and supported" eithen :by said insulators or by. the frame 17 and mayialso be-completely immersed in the 011 The lenetofrthe-oil in the. container is adapted preferably to be-at suchwidistance belowthe {surface of..the ground-that the main portion oibhe-body of'oil may behelow fr st: legrel. whereby the. switeh..will-bee subjeetedio. the least. temperature variation. although, in: any, event, the temperature Va ,riations,willi'xbe.v reduced. over atmospheric tagger-attire. variations, suitably abme thesuwfiace of the ground: as at. 129,.and,.the.container' may be closed by the cpver 23..whichemay beremovable or not, assdesired, Insulators 24 are. supporterhby thecover through which the switch: leads 25: are passed to connect the. stationary switch memhersiwith -the. line. 26 which may be supportedbythe towersfi'i'. .The cover. 23-may be provided with a manhole 28 by which access to the interior of the switch may be-obtained andthe manholemayalso serveas a vent for the switch. v

The. circuit leads for :the electricallywcoutrolled switch-.operatingmechanism may be contained in the conduit 29. which. extends through the cover into the switch.

By reason. of theconstruction. above set forth:a relatiyely...great expansion chamber B'is prowidedabove thezoil in-the switch whereby. the, interrupting capacity of the switch may=becpmparatively great.

The -framed? withl 'ts connected components-mayhe-drawn out f the switch, for, in

ewall of ii eoilcontamer may extendmotion and repair, when desired, and the oil in the switch may be-drawn .out by suitable means, as pumps, not shown.

it will he noted that, with the construction above set forth, elaborate oil receptacles, insulators and the like are obviated. Transportation expenses are reduced as the insulators, switch-members, operating mechanism.. and switch frame, which constitute practically all the switch components not fabricated at the installation location, have but relatively little bulk.

It will also be noted, that, by installing the switch beneath the surfaceof the ground, temperature changes of the oil due to atmos pheric temperature variations are relatively small, as the concrete or cement lining comprising theoil receptacle, and: the ground are, relatively speaking, heat insulators, and the ground by reason of itsv poor heat conducting qualities and rent mass-has its-temperature but slowly c anged in response to atmospheric changes of temperature. It.

furthermore, will act toabsorb an e'lew atcd temperature of the oil clue to-heatin'g-of the switch, and thereby keep the switch cool.

It is obvious that the invention may be embodied in other modifications without departing from the spirit thereof;

"I claiIn:

1. An oil immersed-electric switch. having an oil: receptacle comprising. apit. sunkin the ground and having aiming oi anroilimpervious material, andv stationary; and movable switchrmembers and: an insulating liquid-.containedinswid pit; Y

2.:An oil immersed-e1 trio switch. haying an oil receptacle comprising a pitxsunk 1n:

the ground. and a ement lining in. pit and stationary and movable. switch members. and azbody of. oil contained: in said pita 3. An oil immersed electric switch haying an oilrcceptwle formed ofce nept and contained in, a pit sunk,,.in.tlie ground,..-and. movable and. stationary switch members contained in. the ;oil..i1r; said receptacle.

4.. An oi 'immersedelectnc sw tch having allaOil receptacle comprising-a pit sunk in the ground and-a wall of oilfimpery ious ma teriall'ning'the stiles and bottom ofthe Pit-Sa wall eaten a ve. the ur aeae theground, a cover receiyed' on. 0i. Said Wall, and swi ch member and' 9t1' reid aswd re eptacle- 5 An. oilimmersed electric switch hav ng a ec ptacle. ra ged t -ant i a ad y oil el th u ace of th eve ed s r ri d. b sa a a k: .a a sur ce.

of the, group and switch members. immerseglin the oil in said receptacle.

6. An.- electric switch haying. ancil re ceptacle comprising. a we1l..s unk below the surfaceof the groundadapted. to. contain oil. and switch members immersed in the 7. An electric switch having an oil receptacle comprising a well sunk below the sur face of the ground adapted to contain oil, stationary and movable switch members immersed in the oil in the well, a cover over the well at the surface of the ground and insulators carried by said cover adapted to insulate circuit leads extended to said stationary switch members.

8. An oil immersed electric switch having a receptacle adapted to contain oil and an expansion space above the oil, a cover for the receptacle, movable and stationary switch members disposed beneath said cover and submerged in the oil in said receptacle, insulators carried by said cover, and leads extended through said insulators and connected with said stationary switch mem bers.

9. An oil immersed electric switch having a receptacle adapted to contain oil and an expansion space above the oil, a cover for the receptacle, a frame carried 1) said receptacle and stationary and mova 1e switch members and operating mechanism all supported by said frame and submerged in the oil in said receptacle, insulators carried by said cover, and leads extended through said insulators to said switch-members.

10. An oil immersed electric switch comprising a receptacle adapted to contain oil, stationary and movable switch members and switch operating mechanism, all submerged in the oil in said receptacle, said stationary switch members comprisin insulators having contact members at t e bottom ends thereof and conductors extended through said insulators and connected with said contact members, and circuit leads entering the oil in said receptacle and connected with the upper ends of the conductors in said submerged switch members.

11, An oil immersed electric switch having an oil receptacle formed with cement walls, supports projecting'inwardly from said walls, a frame supported by said supports and stationary and movable switch members and operating mechanism carried by said frame.

12. An oil immersed electric switch having an oil receptacle formed with cement walls, supports embedded in said walls and projecting into the oil space, a frame supported by said supports and stationary and movable switch members carried by said frame.

In testimony whereof, I have signed my name to this specification.

GEORGE A. BURNHAM. 

